Chen add stop using js

https://trello.com/c/cSAGRMdR/58-as-a-user-i-can-drag-to-reorder-trip-stops

![add and delete stop using js](https://cloud.githubusercontent.com/assets/3759510/5254377/ec01585a-797d-11e4-8cca-34b89735ede4.gif)